White matter fiber pathways are key structural components of the brain and its functional organization. The limbic system carries a great deal of its anatomic connectivity via the cingulum bundle. By allowing the in vivo delineation of the stem of the major fiber pathway systems, diffusion tensor magnetic resonance imaging has opened a new window into the detailed structure of the white matter in health and disease. Topographic, biophysical, and volumetric information about fiber tracts will provide a more complete understanding of the brain. By appreciating its interconnections, the precise anatomical knowledge of the cingulum bundle will improve our understanding of the limbic system and may enable improvements in the assessment and treatment of neuropsychiatric disorders. In this study, the stem of the cingulum bundle was investigated and defined in terms of its trajectory, anisotropy, and volume, in four normal human subjects, using diffusion tensor imaging.